In modern aircraft, in order to form cabin windows, normally window frames are inserted into corresponding fuselage cutouts and firmly connected to the outer skin of the aircraft. The window frames are covered or lined by means of a so-called window funnel, which is essentially a funnel-shaped deformation of the side panelling. Typically, a plurality of window panes are inserted into the window funnel. The window funnel has an inner side and an outer side (also called a rear side). Normally, a foam ring is fitted on the outer side of the window funnel, in order to prevent the outer side of the window funnel and adjoining elements of the window frame from being visible to a person looking from outside through the cabin window in the direction of the window funnel. Further functions of the foam ring are as a dust screen and light screen.
FIG. 1 shows, by way of example, a window region 1 in an outer wall region 2 of an aircraft.
FIG. 2 shows half of the window region 1 shown in FIG. 1, enlarged. In the outer wall region 2 there is provided a window funnel 3 which penetrates through the outer wall region 2. A window shade 4 and a first window pane 5 are provided on and inside the window funnel 3, respectively. A second window pane (outer glazing 6) is provided above the window funnel 3. A panelling 7 is provided in the outer wall region 2. The second window pane 6 is fixed in the outer wall region 2 by means of a clamping element (a so-called retainer) 8, which is connected to an outer skin of the aircraft.
On an upper part of an outer side 9 of the window funnel 3 there is provided a foam ring 10. The foam ring 10 is fastened by means of an adhesive layer (not shown) and has, in this example, the geometry shown in FIG. 3. The disadvantage of the arrangement shown in FIG. 2 is that the foam ring 10 can become detached from the adhesive layer owing to shearing forces. This may result in gaps between the outer side 9 and the foam ring 10, which is undesirable since the function of the foam ring 10 as a dust and/or light screen is then no longer guaranteed. If the foam ring 10 becomes completely detached from the outer side 9, the outer side 9 and part of the outer wall region 2 opposite the outer side 9 may possibly even be visible to a person looking along the direction indicated by arrow A.